1. Field of the Invention
It is well known in the art that oxygenated organic compounds may be synthesized from organic compounds containing olefinic linkages by a reaction with carbon monoxide and hydrogen in the presence of a catalyst containing cobalt in an essentially three-stage process. In the first stage, the olefinic material and proper proportions of CO and H.sub.2 are reacted in the presence of the catalyst to give a product consisting predominantly of aldehydes containing one more carbon atom than the reacted olefin. The catalyst in the first stage of the process has generally been added in the form of high molecular weight fatty acid salts of the catalytically active metal. These salts are soluble in the liquid olefin feed or in the liquid reaction products and have been supplied to the first stage as hydrocarbon solutions or dissolved in the olefin feed. Also it has been proposed to employ catalyst deposited on a carrier in the form of a slurry and employ the supported cobalt material in the slurry rather than the metal soap. Regardless of the form of catalyst employed, prior investigations have concluded that the active form of the catalyst utilized in the reaction is a metal carbonyl formed by a reversible reaction of the catalyst with the CO and H.sub.2 at hydroformylation conditions. This theory is supported by the fact that preformed catalysts, obtained by subjecting the metal salt to hydroformylation conditions prior to introduction of the olefin feed, have shown a marked reduction in induction time, which is the time required to initiate reaction measured from the instant that reaction conditions are first obtained. Regardless of the form of catalyst used, prior art investigators have found that the oxygenated organic mixture obtained from the first stage of the reaction contained, dissolved therein, compounds such as carbonyls and molecular complexes of the metal catalysts. The organic mixture is therefore treated in a second stage to cause removal of soluble metal compounds from the organic material. This treatment is necessary to remove the metal compounds since they separate out on the catalysts used and plug transfer lines and heat exchangers. This treating has been carried out, for example, by the use of acids or heat. The catalyst-free material is then generally hydrogenated to the corresponding alcohols or it may be oxidized to the corresponding acids.
2. Prior Art: Catalyst Preparation
Catalysts of the present invention are made by the metal vaporization synthesis technique (J. R. Blackborow and D. Young, "Metal Vapour Synthesis in Organometallic Chemistry", Springer-Verlag, New York 1979). By this technique, metal is vaporized in a furnace under pressure of 10.sup.-3 to 10.sup.-8 Torr or less and at temperatures which vary according to the metal, usually from 800.degree. C. to 2500.degree. C. Furnaces used for the metal vaporization synthesis technique include electron beam guns, resistance heated furnaces, laser beam heating, hot filaments and electric arcs. Electron beam guns and resistance heated furnaces are convenient and preferred methods for catalyst preparation.
3. Prior Art: Hydroformylation
Hydroformylation refers to the reaction of an olefin with hydrogen and carbon monoxide in the presence of a cobalt catalyst to produce aldehydes containing one carbon atom more than that of the olefin in the feed. The reaction is carried out by bringing the olefin and slurry of cobalt catalyst in contact with carbon monoxide and hydrogen. Commercially, the carbon monoxide and hydrogen are supplied by synthesis gas, with the ratio of H.sub.2 :CO usually being 1:1. Although equal molar quantities of synthesis gas and olefin are consumed, normally synthesis gas is supplied in excess. This reaction is represented generally, by the hydroformylation of propylene to give n-butyraldehyde and i-butyraldehyde in the ratio of 3:2. ##STR1##
U.S. Pat. No. 3,352,924 describes cobalt substituted zeolite catalysts which require a synthesis gas pressure of about 2500 psig for hydroformylation activity. P. Centola et al., Chim. Ind. (Milan), 54, 775 (1972) describes cobalt exchanged zeolites for hydroformylation of propylene at pressures of 2000 to 4500 psig.
In commercial practice, the process involves a second step in which aldehydes are reduced with hydrogen to primary alcohols. The liquid oxygenated product obtained from hydroformylation in the presence of the catalyst of this invention may be fed directly to a hydrogenation zone where it is hydrogenated under conventional conditions to obtain substantial yields of primary alcohols. Conventional hydrogenation conditions typically include pressures in the range of 2,000 to 4,000 psig and temperatures in the range of 300.degree. F. to 550.degree. F. Hydrogenation conditions will vary with the choice of catalyst with nickel, molybdenum sulfide or the like representing conventional choices. Typical hydrogenation conditions may be found in U.S. Pat. No. 2,771,493.